Strategies on solar observation of Atacama Large Millimeter/submillimeter Array (ALMA) band-1 receiver

Chiong, Chau-Ching; Chiang, Po-Han; Hwang, Yuh-Jing; Huang, Yau-De

doi:10.1117/12.2232254

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…If no attempt is made to filter out or attenuate the incoming RF power, the system noise power injected into the receiver will drive the last LNA stage of each pixel/polarization into saturation. A technique will be explored to de-tune the bias of the LNAs and lower their total gains, thus avoiding saturation, as described in [50]. The bias de-tuning can be performed remotely using the "GAIA" digital LNA bias board, which will be discussed later in Section X.…”

Section: C) Receiver Looking At the Sun Through Solar Filtermentioning

confidence: 99%

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

et al. 2022

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We report on the feasibility study of a W-band multibeam heterodyne receiver for the Sardinia Radio Telescope (SRT), a general purpose fully steerable 64-m diameter antenna located on the Sardinia island, Italy, managed by INAF ("Istituto Nazionale di Astrofisica," Italy). The W-band front-end is placed at the telescope Gregorian focal plane and will detect radio astronomy molecular spectral lines and broadband emission in the 3 mm atmospheric window. The goal specification of the receiver is a 4×4 focal plane array operating in dual-linear polarization with a front-end consisting of feed-horns placed in cascade with waveguide Orthomode Transducers (OMTs) and LNAs (Low Noise Amplifiers) cryogenically cooled at ≈20 K. The instantaneous FoV (Field of View) of the telescope is limited by the shaping of the 64-m primary and 7.9-m secondary mirrors. The cryogenic modules are designed to fit in the usable area of the focal plane and provide high-quality beam patterns with high antenna efficiency across the 70-116 GHz Radio Frequency (RF) band. The FoV covered by the 4×4 array is 2.15×2.15 arcmin 2 , unfilled, with separation between contiguous elements of 43 arcsec. Dual-sideband separation (2SB) down-conversion mixers are placed at the cryostat output and arranged in four four-pixel down-conversion modules with 4-12 GHz Intermediate Frequency (IF) bands (both Upper Side Band and Lower Side Band selectable for any pixel and polarization). The receiver utilizes a mechanical derotator to track the parallactic angle.

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Section: C) Receiver Looking At the Sun Through Solar Filtermentioning

confidence: 99%

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

et al. 2022

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A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment

et al. 2018

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We describe the design of a cryogenic rotation stage (CRS) for use with the cryogenic half-wave plate (CHWP) polarization modulator on the POLARBEAR-2b and POLARBEAR-2c (PB2b/c) cosmic microwave background (CMB) experiments, the second and third installments of the Simons Array. Rapid modulation of the CMB polarization signal using a CHWP suppresses 1/f contamination due to atmospheric turbulence and allows a single polarimeter to measure both polarization states, mitigating systematic effects that arise when differencing orthogonal detectors. To modulate the full detector array while avoiding excess photon loading due to thermal emission, the CHWP must have a clear-aperture diameter of > 450 mm and be cooled to < 100 K. We have designed a 454-mm-clear-aperture, < 65 K CRS using a superconducting magnetic bearing driven by a synchronous magnetic motor. We present the specifications for the CRS, its interfacing to the PB2b/c receiver cryostat, its performance in a stand-alone test, and plans for future work.Cosmic microwave background (CMB) polarization is a powerful probe of cosmology. Particularly, the "B-mode" CMB polarization pattern can be used to probe gravitational lensing on arcminute angular scales [1, 2] and primordial gravitational waves on degree angular scales [3][4][5]. In order for a single telescope to characterize small and large scales simultaneously, it must observe with high resolution over a large sky area, requiring both a large primary aperture and good low-frequency (or "1/f") noise performance [6].Rapidly-rotating half-wave plates (HWP) are a common technique to modulate CMB polarization and reduce the impact of low-frequency noise on experiment sensitivity [6][7][8][9][10][11][12].

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Strategies on solar observation of Atacama Large Millimeter/submillimeter Array (ALMA) band-1 receiver

Cited by 2 publications

References 3 publications

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment

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